EXAM 3: Chapter 6 Flashcards
catabolism
breakdown of molecules for energy, reducing potential, and building blocks
How do cells produce ATP
Substrate level phosphorylation
Photophosphorylation
oxidative phosphorylation
substrate level phosphorylation
enzymatically coupled reaction producing ATP
Transfer of a phosphate group from a reactive intermediate during catabolism to ADP
What does coupled reaction mean?
Releases energy when P is pulled off
Uses energy when P is put onto AT
Where does substrate level phosphorylation occur
heterotrophs in cytoplasm
Chemoorganotrophic catabolic pathways
breaks other sources into intermediates and funnels into glycolytic pathway
- Saves on genome space
- More efficient
Aerobic respiration uses
Glycolytic pathways
TCA cycle
Electron transport chain with oxygen as terminal electron acceptor
Three common routes for breakdown of glucose
Embden-meyerhof pathway: most common
Pentose phosphate pathway: bacteria tend to use for fermentation
Entner-Duodoroff pathway: specific to bacteria
Where does Ebden-Meyerhof pathway (glycolysis) occur
cytoplasm/ cytoplasmic matric
Embden-meyerhof has two phases
Energy investment/ 6 carbon
Energy generating/ 3 carbon
Energy investment phase
Addition of phosphate (breaking ATP into ADP) primes the pump
Second addition of ATP
Ends this phase with a 6 Carbon
Energy generating phase
Generates electron acceptor in form of NADH
Generates energy through substrate phorylation
Condensation reaction
Energy generated
Summary of glycolysis
Start: glucose, 2ADP, 2NAD+
End: 2 pyruvate, 2ATP, 2NADH
- Invest 2 ATP
- Gain 4 ATP
- So net is 2ATP
Tricarboxylic Acid cycle major role
source of carbon skeletons for biosynthesis
Where does TCA occur
Eukaryotes: occurs in mitochondria
Prokaryotes: occurs in plasma membrane
TCA cycle process
begins with pyruvate from glycolysis
The transition step which generates electron carrier and starts TCA with Acetyl-CoA
- Tightly regulated
- Irreversible
Also tightly regulated where it interacts with ETC
Summary of TCA
For each Acetyl-CoA oxidized TCA generates:
2 molecules of CO2
3 molecules of NADH
1 molecule FADH2
1 molecule GTP
Remember 2 Acetyl-CoA are produced per starting molecule of glucose
TCA regulation
Allosteric regulation- isocitrate dehydrogenase
Feedback inhibition:
- Increase in ATP/ high concentration NADH causes negative regulation
Precursor activation
- ADP/NAD will cause positive regulation
Oxidative phosphorylation
Chemiosmotic model
Electrons passed through electron transport system
- Generates proton gradient
- Energy from flow of protons can be used to drive the enzyme ATP synthase
chemiosmotic model
As electrons flow in, it generates energy to pump protons and build a gradient; this potential energy is used to run ATP synthase
The bigger the redox potential…
the greater the proton gradient
the more ATP produced
Redox reaction
Redox reaction: transfer of electrons from one molecule to another
Oxidation- loss of electron
Reduction- fain of election
redox potential (E)
tendency of a molecule to acquire electrons
negative E
doesnt like to accept electrons
positive E
likes to accept electrons
How do electrons flow in mitochondrial ETC
from carriers (donors) wit more negative reduction potentials to carriers (acceptors) with more positive reduction potentials
Why does ETC have 4 complexes?
Dont capture as much energy if it was one step
Need little steps because the differential is so large
How does ETC work
Complex 1: proton pumper and most negative redox potential
Complex 2 donates to complex 3 (proton pumper)
Complex three donates to complex 4 (proton pumper and most positive)
Where does ETC occur
Eukaryotes: in mitochondrial membrane
prokaryotes: in plasma membrane
Difference in bacterial/Archael ETC
Different electron carriers
May be branched
May be shorter
Pumps less protons, has smaller gradient, thus less ATP
What drives ATP synthesis
PMF
ATP synthase
F0 embedded in membrane
F1 in cytoplasm
As protons move through it causes gamma subunit to spin and change active site conformation
This facilitates addition of phosphate onto ADP
Takes 3H to generate 1 ATP
Where does ATP synthesis occur
Eukaryotes: mitochondrial inner membrane
Bacteria: inner plasma membrane
What is ATP yield in eukaryotes
about 34 ATP
Aerobic respiration
Uses electron carriers other than O2
Generally yields less energy because E of electron acceptor is less positive than that of O2
